Process for preparing perfluoroalkyl and omega - chloroperfluoroalkyl - 3 - acyloxy - 1,3 - butadienes and products and polymers thereof



United States Patent 3,424,732 PROCESS FOR PREPARING PERFLUOROALKYL ANDto CHLOROPERFLUOROALKYL 3 AC- YLOXY 1,3 BUTADIENES AND PRODUCTS ANDPOLYMERS THEREOF William J. Middleton, Wilmington, Del., assignor to E.L du Pont de Nemours and Company, Wilmington, Del., a corporation ofDelaware No Drawing. Filed Nov. 22, 1965, Ser. No. 509,174 US. Cl.26082.1 6 Claims Int. Cl. C07c 69/14; C08f 3/52, 15/16 This applicationrelates to novel acyloxy-1,3-butadienes, to a process for theirpreparation and to polymers therefrom.

The monomeric compounds of this invention are perfluoroalkyl andw-chloroperfiuoroalkyl-3-acyloxy-1,3-butadienes having the generalformula wherein R and R taken separately can be the same or differentand represent perfiuoroalkyl or w-ChlOIOPCffluoroalkyl containing 1 to 4carbon atoms, R and R taken together represent perfiuoroalkylenecontaining 3 to carbon atoms, and R is a saturated aliphatic or aromatichydrocarbyl group selected from the group consisting of alkyl containing1 to 10 carbon atoms, aralkyl containing 7 to 14 carbon atoms, arylcontaining 6 to 14 carbon atoms, and alkylaryl containing 7 to 14 carbonatoms. These monomers can behomopolymerized and copolymerized withcopolymerizable monomers containing ethylenic unsaturation having thegeneral formula It has been found that the compounds of Formula 1 can beprepared by pyrolysis of the esters of 4,4-bis(perfluoroalkyl)-4-hydroxy-1,2-butadiene and4,4-bis(w-chloroperfiuoroalkyl)-4-hydroxy-1,2-butadiene having thegeneral formula R o0('1cH=C=cH2 wherein R R and R are the same asdescribed above.

Three reactions are to considered with the process embodiment of thisinvention: (1) the methylacetylene reaction which is illustrated by thefollowing equation (2) the esterification reaction in which the4-hyd-roxy- 1,2-butadiene produced by the methylacetylene reaction isacylated; the esterification reaction is illustrated by the followingequation wherein X is selected from the group conisting of halogen andacyloxy and B is a basic substance selected from,

Patented Jan. 28, 1969 where R R and R are as described above.

In carrying out the methylacetylene reaction according to process ofthis invention, fluorinated ketones are heated at -200" C. with lessthan stoichiometric amounts to greater than stoichio'metric amounts ofmethylacetylene, but best results are obtained with at least a molarexcess of methylacetylene. The reaction is usually carried out for aperiod of time of 10-100 hours. Autogenous pressures are used. Themethylacetylene reaction product is separated from the reaction mixtureby conventional distillation and crystallization techniques. In order toobtain optimum yields of 1,2-butadienes, the methylacetylene reaction iscarried out in the presence of a free-radical scavenger such aspolyhydric phenols, for example, hydroquinone, catechol andtert-butyl-catechol; quinones, for example, benzoquinone,naphthoquinone, choranil, and 9,10 phenanthrenequinone; and substitutedaromatic amines, for example, hydroxydimethylaniline,nitrosodimethylaniline, phenothiazine and 4-hydroxy-1- naphthylamine.

Among the perfluoroalkyl and the w-chloroperfluoroalkyl acyclic ketones,and perfiuoro cyclic aliphatic ketones used in the methylacetylenereaction are: perfluoroacetone, perfluorobutanone-Z,perfiuoropentanone-Z, perfluoropentanone-3, perfluorocyclobutanone,perfiuorocyclopentanone, perfluorocyclohexanone, bis(chlorodifiuoromethyl)ketone, bis(B-chlorotetrafiuoroethyl)ketone andother omega chloroperfluoroalkyl acyclic ketones.

In carrying out the esterification reaction according to process of thisinvention, the 1,2-butadiene prepared by the methylacetylene reaction isdissolved in an aprotic solvent such as dimethoxyethane (glyme), diethylether or tetrahydrofuran containing a basic substance selected from thegroup of alkali metals of Group IA of the Periodic Table of Element-s,alkaline-earth metals of Group IIA of the Periodic Table of Elements andderivatives of said alkali and alkaline-earth metals such as alkali andalkaline-earth hydrides, alkali and alkaline-earth amides, and loweralkyl alkali and alkalineearth organic compounds. Examples of thesebasic substances are lithium, sodium, potassium, lithium hydride,rubidium hydride, lithium amide, sodium amide, isobutyllithium,methylsodium, ethylcesium and methylmagnesium halide. For best results,a suspension of the alkali hydrides or alkaline-earth hydrides in anaprotic solvent is used.

Among the acylating agents suitable for the esterification reaction are:carboxylic acid anhydrides and carboxylic acid halides derived fromaliphatic carboxylic acids containing up to 10 carbon atoms such asacetic, propionic, n-butyric, isobutyric, pentanoic, hexanoic,heptanoic, octanoic, nonanoic and decanoic acid; derived fromaralkanecarboxylic acids containing 7 to 14 carbon 1 The Periodic Tablereferred to herein is that set forth in Demings General Chemistry, JohnWiley & Sons, Inc., 5th ed., Chapter 1.

atoms such as ot-phenylacetic, a-phenylpropionic, ,G-phenylpropionic,a-phenyl-n-butyric, B-phenyl-n-butyric, 'y-phenyl-n-butyric, andcorresponding aralkanecarboxylic acids wherein the aryl group is alkylsubstituted such as tolylmethyl .and xylylmethyl; and aromatic and alkyland aryl 5 substituted aromatic carboxylic acids containing 6 to 14carbon atoms such as benzoic, a-naphthoic, B-naphthoic, o-toluic,m-toluic, p-toluic, and phenyl'benzoic acid. The above carboxylichalides are fluorides, chlorides, bromides, or iodides.

In general, the acylating agent is added to the reaction mixture at atemperature of from to +100 C. The ester is isolated by conventionalmeans, for example, by washing with water until the water layer isneutral to litmus paper followed by distillation of the organic layer atatmospheric or less than atmospheric pressures.

In carrying out the pyrolysis reaction according to the process of thisinvention, the ester produced in the esterification reaction is heatedto 400-600 C. by passing it through a heated tube at autogenouspressures of subatmospheric to +50 atmospheres. The pyrolysis isconducted in a metallic or ceramic tube, said tube being constructedfrom metals such as platinum, copper, stainless steel, and nickel and inceramics, for example, high silica containing glasses.

The monomeric compounds of this invention can be homopolymerized andcopolymerized in bulk, in solution, or in emulsion by free-radicalinitiation. Initiation may be accomplished by the use of conventionalfree-radical organic and inorganic peroxy and aliphatic azo initiatorssuch as isopropyl peroxycarbonate; acetyl, lauroyl, and benzoylperoxide; ammonium persulfate or hydrogen peroxide-reducing agentmixtures, which are commonly known as redox systems; and2,2-azobisisobutyronitrile and related azo initiators. Chain transferagents such as mercaptans, which are molecular weight modifiers may beused in free-radical polymerizations when control of the molecularweight of the polymer is desired. Initiation using ionic initiators suchas BF may also be used. The initiators are employed in the usualconcentration range of 0.01 to 10% of the weight of the monomer beingpolymerized.

Suitable copolymerizable monomers containing ethylenic unsaturation arevinyl containing compounds such as, styrene, vinyl chloride, vinylacetate, methyl .acrylate, methyl methacrylate, acrylonitrile,vinyltoluene; aliphatic conjugated dienes such as 1,3-butadiene,chloroprene, isoprene, and vinylidene containing compounds such asvinylidene chloride and fluoride.

The proportion of the monomeric compounds of this invention in thesecopolymers is preferably 5 to 85 weight percent, but any proportion maybe used.

The following examples further illustrate the invention in greaterdetail.

EXAMPLE I (A) 4-hydroxy-5,5,5-trifluoro-4-trifiuoromethyl-1,2-pentadiene u i CF3-C-GF3 CHz-CECH HOGCH=C=CH2 A 400 ml. stainless-steelbomb charged with 100 g. of methylacetylene, 100 g. ofhexafiuoroacetone, and 1 g. of hydroquinone was heated at 150 C. for 48hours with agitation. The bomb was cooled and vented, and the residuewas distilled to give 70.5 g. (57%) of 4-hydroxy-5,5,5-trifluoro-4-trifiuoromethyl-1,2-pentadiene as a colorless oil,B.P. 105-106 C., n 1.3477. The infrared spectrum contains bands at 503and 5.0911. for the allene (C-=C=C) group.

Analysis.-Calcd. for C H F O: C, 34.97; H, 1.96; F, 55.35. Found: C,35.41; H, 2.16; F, 55.23.

4 hydroxy 5,5,5 trifiuoro 4 trifluoromethyl 1,2- pentadiene, 20.6 g.,was added dropwise with stirring to a suspension of 4.5 g. of 54% sodiumhydride (in mineral oil) in ml. of 1,2-dimethoxyethane. The reactionmixture was cooled in an ice bath and then 7.9 g. of acetyl chloride wasadded dropwise with stirring. Themixture was poured into 200 ml. ofwater and the lower layer that formed was separated, washed with water,and dried over magnesium sulfate. Distillation gave a yield of 22.2 g.as a colorless liquid, B.P. -136", 11 1.3668. The infrared spectrumcontained bands at 5.55, 5.01 and 5.09

Analysis.Calcd. for C H F O C, 38.72; H, 2.44; F, 45.95. Found: C,38.77; H, 2.52; F, 44.63.

(C) 5,5 ,5 -trifluoro-4-trifiuoromethyl-2-acetoxyl ,3-

4 Acetoxy 5,5,5 trifiuoro 4 trifiuoromethyl 1,2- pentadiene, 14 g., wasadded dropwise under a nitrogen atmosphere over a period of 1 hour intoa 0.5 in. diameter silica glass tube heated to a temperature 500i5 C.and inclined at a 45 angle and the pyrolysate was collected in a cooledtrap. Distillation of the pyrolysate through a spinning band column gave8.0 g. (57%) of 5,5,S-trifluoro-4-trifluoromethyl-2-acetoxy-1,3pentadiene as a colorless liquid, B.P. 6668 C. at 22 mm. Hg. Theinfrared spectrum showed one carbonyl and two C=C bands. The protonmagnetic resonance spectrum showed a singlet at 2.13 ppm. (area 3), amultiplet at 5.52 ppm. (area 2), and a broad absorption at 674 p.p.m.(area 1) from (CH Si used as an internal reference The fluorine- 19magnetic resonance spectrum showed a pair of quartets (I=7.5 c.p.s.) at2.04 and 9.13 ppm. from the resonance of CFCl CFCl used as an externalreference.

Analysis.Calcd. for C H O F C, 38.71; H, 2.44; F, 45.94. Found: C,39.29; H, 2.90; F, 45.34.

EXAMPLE II Poly(5,5 ,5-trifiuoro-4-trifluoromethyl-Z-acetoxy-1,3-pentadiene) A 750mg. sample of 5,5,5-trifiuoro-4-trifiuoromethyl-2-acetoXy-1,3-pentadiene was placed in a dry, heavywalled glass tube and10 mg. of 2,2'-azobisisobutyronitrile was added. The tube was evacuatedand flushed several times with nitrogen, sealed, and then heated to 60C. in a Water bath. When the liquid began to cloud, the heating wasdiscontinued by removing the bath. The suspension that formed wasallowed to stand for 17 hours at room temperature. The white polymerthat formed (was collected on a filter washed with methanol and dried. Aclear colorless film 'was pressed at 210 C. and 10,000 lbs. rampressure. The infrared spectrum of this film showed bands at 5 63;]. and5 .97

Analysis.Calcd. for (C H F O C, 38.71; H, 2.44; F, 45.94. Found: C,38.69; H, 2.72; F, 45.62.

EXAMPLE IH Poly(5 ,5 ,S-trifiuoro-4-trifluoromethyl-2-acetoxy-1,3-pentadiene A solution of 3.7 g. of 5,5,5-trifluoro-4-triiluoromethyl-2-acetoxy-1,3-pentadiene in 30 ml. of l,1,2-trichloro-1,2,

EXAMPLE IV Poly( ,5 ,5-trifluoro-4-trifiuorornethyl-2-acetoxy-1,3-pentadiene) polymer 4 Acetoxy 5,5,5 trifluoro 4 trifluoromethyl 1,2-pentadiene, 15.1 g., (0.062 mole) was added dropwise through a /2"platinum tube inclined at a 30 angle and heated over 12" to 500: C. Thepyrolysate was condensed in a trap cooled by ice. The clear yellowliquid that was obtained was heated to 80 100 C., at which temperatureit solidified. The solid polymer was shredded in a blender with water,washed with water, and dried in a vacuum at 50 C. There was obtained 6.5g. of po1y(5, 5,5 trifluoro 4 trifiuoromethyl 2 acetoxy 1,3-pentadiene), as a white powder, which melted above 220 C. A transparentflexible film was pressed from this power at 210 C. and 10,000 lbs. ram.pressure. This film was resistant to most common organic solvents,including acetone, ethanol, ethyl acetate, benzene, toluene,chlorofor-m, carbon tetrachloride, hexane, N,N-dimethylformamide,dimethyl sulfoxide, and methylene chloride.

Analysis.Calcd. for (C H F O C, 38.72; H, 2.44; F, 45.95. Found: C,37.49; H, 2.59; F, 44.70.

The monomeric compounds of this invention are useful for preparingplastics that can be transformed into manufactured articles. Theseplastics are particularly useful in preparing molded articles that comein contact with organic liquids such as oils, gasoline and dry cleaningsolvents because of their resistance to most common organic solvents.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed since obvious modifications will occur to those skilled in theart.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A compound of the formula wherein R and -R taken separately can bethe same or different and are selected from the class consisting ofperfluoroal-kyl and w-chloroperfluoroalkyl containing 1 to 4 carbonatoms, [R and R taken together is perfiuoroalkylene containing 3 to 5carbon atoms, and R is a saturated aliphatic or aromatic hydrocarbylgroup selected from the class consisting of alkyl containing 1 to 10carbon atoms, aralkyl containing 7 to 14 carbon atoms, aryl containing 6to 14 carbon atoms, and alkylaryl containing 7 to 14 carbon atoms.

2. The compound of claim 1,5,5,5-trifluoro-4-trifluoromethyl2-acetoxy-1,S-pentadiene.

3. Process for preparing a compound of claim 1 by pyrolyzing attemperatures of 400-600 C. at autogenous pressure a compound of theformula R1 0 H2C=C=CH--(:JO-("}-R3 wherein R R and R are as defined inclaim 1.

4. Process for preparing the compound of claim 2 by pyrolyzing 5,5,5trifluoro 4 trifluoromethyl 4 acetoxy-l,2-pentadiene conducted attemperatures of 400- 600 C.

5. A solid synthetic polymer selected from the group consisting ofhomopolymers and copolymers of the compounds of claim 1 andethylenically unsaturated compounds having the general formula 6. Thesolid synthetic polymers of claim 5 selected from the group consistingof poly(5,5,5 trifluoro 4- trifluoromethyl 2 acetoxy 1,3 pentadiene),copolymers of 5,5,5 trifluoro 4 trifluoromethyl 2 acetoxy-1,3-pentadiene and chloroprene, copolymers of 5,5,5-trifluoro 4trifiuoromethyl 2 acetoxy 1,3 pentadiene and styrene, and copolymers of5,5,5-trifluoro-4-trifiuoromethyl-Z-acetoxy-1,3-pentadiene andvinylidene fluoride.

References Cited UNITED STATES PATENTS 2,418,708 4/1947 Gwynn et a1260488 US. Cl. X.R.

5. A SOLID SYNTHETIC POLYMER SELECTED FROM THE GROUP CONSISTING OFHOMOPOLYMERS AND COPOLYMERS OF THE COMPOUNDS OF CLAIM 1 ANDETHYLENICALLY UNSATURATED COMPOUNDS HAVING THE GENERAL FORMULA